Hearing testing



March 1937- J. L. BLOOMHEART 2,072,705

HEARING TESTING Filed July 17, 1935 2 Sheets-Sheet l am cnuvucrwu Patented Mar. 2, 1937 UNITED STATES PATENT OFFICE 2,072,705 I HEARING TESTING Application July 17, 1935, Serial No 31,810

Claims.

This invention relates to sound equipment oraudiometric devices or apparatus.

This invention has utility in audibly and controllably generating tones, especially in testing 5 and checking hearing of individuals on definite frequency and volume.

Referring to the drawings:

Fig. 1 is a plan view of a panel for an embodiment of the sound testing device under the invention herein;

Fig. 2 is a detail view of the drive from the intensity indicator to the record-effecting indicator in the device of Fig. 1;

Fig. 3 is a section on the line III-J11, Fig. 1;

Fig. 4 is a detail view of the receiver as adapted to transmit bone conduction to the user;

Fig. 5 is a wiring diagram of electrical features of the device of which the panel is shown in Fig. 1;

Fig. 6 is a side elevation of the device in the cabinet;

Fig. '7 is a view of a side of a record as adapted to be developed at the indicator; and

Fig. 8 is a detail view of the receiver as adapted to the ear.

Cabinet I is shown provided with closure 2 beneath which is panel 3 as an instrument board. In carrying out the invention herein, such for ear or so-called air conduction, may have, as energy source, dry cells 4 say to 90 volts. It is convenient for this purpose to adopt battery setup such as used in radio work. Lines 8, 3, from the dry cell 4 may be effective through switch 1 for connecting these lines respectively to lines 3, 9. Line 3 is connected through gas-providing gap or neon oscillating lamp or tube III with line ll, connected by variable condensers l2 and vgriable resistances I3 to lines l4, l5, l3, l1, l3,

The circuit tothe'se lines from the predetermined variable condensers l2, l3, has its frequency controlled due to the cooperation of the tube III. The circuit is completed with the line 9 through primary winding 23 of transformer and line 2! to frequency selector switch 22.

In determining these values for frequency when the check-up is for the human ear, the tones may be of frequency for a succession of notes C on the scale. For instance, the line l4 when connected to the line 2| may be'for C as 64 vi.- bration frequency per second. The line I5 may be to note C thereabove, say 126 vibration frequency persecond, and so on through the scale of these predetermined frequencies.

From this primary of the transformer, in-

duction is effective through iron core 23 of thistransformer to secondary winding 24. From the secondary 24, line 25 may extend to potentiometer 26. From the opposite side of this winding 24 line 21 extends to the opposite side of this potentiometer 26. From the line 23 to the potentiometer 26, there is line 23 to switch 23, thence by line 30 to switch 3|. From the switch 31 extends line 32 to terminal 33 on the cabinet and thence by line 34 to receiver 33 of head set 36.

At the potentiometer 26 there is adjustment 31 for intensity control of the frequency operable by rotating handle 38 (Fig. 1). This adjustment 31 at the potentiometer has line connection 33 to the switch 29, and thence by line 40 to terminal 4| on the panel. From this terminal 4| extends line 42 as a common lead not only to the right receiver 35 of the head set 36 but to left receiver 43. From this receiver 43 extends line 44 to terminal 44' on the panel, and thence to the switch 3|. This switch 3| is thus a selector for the receiver 35 at the right ear or the receiver 43 for the left ear. In the diagnosis the switch 22 may be adjusted for frequency change and the switch 31 for intensity control. These receivers are cushioned.

In checking up with the patient as to whether or not there may be head noises or other disturbances interfering, the operator may close push button switch 45 and thus short-circuit between the lines 25, 21, from the secondary 24. This will render ineffective the frequency selection and potentiometer so that the receiver 35 or 43 will be idle or quiet.

The switch 1 is shown with three positions. As shifted counter-clockwise in the extreme position, the battery 4 is on in supplying energy source for checking through the head set 36. Upon a turning to the right of the switch 1 to mid-position, such is off as to the battery 4 and in fact of! as to energy source, whether battery or line current. Further shifting to the right brings the switch 1 to connect in alternating current power lines for this instrument. Lines 46, 41, to this switch 1 connect in this throwing of the switch 1 to the lines 9, 8, while lines 5 and 3 are out of circuit. In the line 46 is adjustable resistance 43 controllable to render this power supply such as may properly function in conjunction with the condensers, resistances, and transformers, as well as potentiometer, thereby providing a generator frequency source in the electric current supply responsive in the checking or testing of hearing for the user or patient as effective through the receivers 35, 43. Rotation of the handle 38 in controlling the intensity is connected through gearing 49,;53 (Fig. 2) to rotate shaft 5| and thereby locate pointer 52 on scale 53 as a visible indicator of the adjustment obtained at the potentiometer by operating the switch 31.

Differential gearing controlled by shaft 5| operates wheel 5| from which is connected metal tape 54 extending to wheel 55 on shaft, 36. This tape 54 is fixed with the wheels 5|, 55, and thus provides positive rotation means in each direction for the shaft 56 having fixed thereon arm 51 (Figs. 1, 8). This arm 51 has thereon series of plungers 58, 59, 6|), 6|, 62, 63, in similar number and noted value as for the frequencies determined by the adjustment of the switch 22.

Adjacent this arm 51, as movable over felt cushion 51', is guide 64 for notation receiving card 65 having chart 66 thereon with arcs corresponding to the notations for the adjustments of the frequencies 22. Radial lines on this chart 66 correspond to the notations on the dial 53 as disclosed by the pointer 52. It thus follows that, as the switch 31 is adjusted by the knob or handle 38, the intensity as disclosed at the dial 53 is that followed by the arm 51, and it is only necessary that the operator depress the particular plunger corresponding to the notation at the arm 22, thereby punching the chart 66, giving a simultaneous reading of frequency and intensity as found for the air conduction say for the right car. This chart may be similarly printed on the reverse side for the left ear and be moved and inserted in the guides 64 when the switch 3| is turned for checking the patient as to hearing to be investigated in connection with the left ear.

This operation for diagnosismay be as to air or ear and for bone'conduction. The equipment is shown'in a cabinet and is a compact, simple device. It may be used with the electric power from a battery or power current supply.

To this end, with the switch 1 connected to the "power supply lines- 46, 41, the switch 29 may be shifted clockwise, thereby connecting lines 28, 39, to lines 61, 68, and amplifier 69. This amplifier 69 is of a type adapted to radio work and effective to increase the intensity over that as used for thehead set to make the energy source adaptable herein for bone conduction testing. The switch 1 connects the line 46 through line 16 and variable resistance 1| with volt meter 12, thence by line 13 to the amplifier 69. Line 14 from the switch 1 is connected through the line 13 to this amplifier 69. From the variable resistance 1| there is line 15 connected to the amplifier 69. Lines 16, 11, from this amplifier extend to primary 18 of output transformer having iron core 19 and secondary 80,. From this' secondary 80, line 8| extends to terminal 82 on the panel 3, and line 83 extends to terminal 84 In diagnwis there may be occasion for exploration near the right and left ears. Bone conduction diagnosis is assisted by the use of the potentiometer in the range available by the amplifier 69. There is assistance in the frequency control. Accordingly, chart on the card 65 provides a convenient set-up of scale relations showing recording punch 90' located not only for the frequency but for intensity.

This bone conduction chart 90 is di posed with the chart 66 for the right ear. Accordingly, bone conduction may be taken at the same time as the air or ear conduction for the same side of the head. In placing the card 65 in position for the bone conduction, it will be with opening 9| inserted to embrace the stem or shaft 56 instead of opening 92. With this right ear side up, this means the lower right hand corner of the card is placed in the upper left hand position. For the reverse or left side reading, the printing on the opposite side of the card 65 is available, for the action of the punches clearly shows the side upon which the punch is eifectlve.

Lines 93, 94, from the amplifier 69 may be taken oil? as desirable to supply current of say 2 volts and thus allow the operator readily to observe the dial 53 as illuminated by bulbs 95. Additionally, from these lines 93, 94, there may be pilot lamp 96 from the line 94 in line 91 to switch 98, which as closed completes circuit by way-of line 99 to the line 93. This pilot lamp or jewel 96 at the panel is a signal or indication means from the patient as to whether or not the machine is functioning from a current source of supply, and ifv so functioning, the operator may control the cut-out in supplementally checking to be effective through the push button 45 in this bone testing as readily as heretofore discussed in connection with the ear or air testing conduction. Cut-out may also be had at "o position for the switch 22 (Fig. 1).

What is claimed and it is desired to secure by United States Letters Patent is:

1. Hearing testing apparatus comprising a source of variable frequency electric current,

means for controlling the frequency of said current, volume control means for said current, an indicator associated therewith, and rotary recordeffecting means coupled to said indicator.

2. In an electric audiometric device having a source of testing current and a volume control, and an indicator therefor, thev combination therewith of a record making device positively driven thereby, said record making device comprising a punch bearing arm rotatably mounted over a suitable record card.

3. An audiometric device comprising a generator of variable frequency testing current, an air conductor applicator, a bone conductor .applicator, circuit means for energizing either applicator, volume control means, and volume recording means associated with said circuit means, said recording means enabling a card punch record to be made of desired volume observations.

4. Hearing testing apparatus comprising a source of variable frequency electric current, means for controlling the frequency of said current, volume control means for said current, an indicator associated therewith, and rotary recordproducing mechanism connected to said indicator and including means'responsive to manual actua-.

JOHN L. BLOOMHEART. 

